Introduction
The pelvic ring fracture refers to a fracture of the bone that interrupts the integrity of the so-called pelvic ring. The term “pelvic ring” (Cingulum membri pelvini) is derived from a cross-sectional view of the pelvis in which the pelvic bones are contiguous and arranged in a ring shape. The pelvic ring represents the connection between the spinal column and the lower extremity.
Its main function is to provide stability in standing and walking. It is decisive for an upright posture, serves as a point of attachment for various muscles and is therefore important for movement. The bony pelvis also protects the inner organs of the lower abdomen.
Definition
A pelvic ring fracture results in a fracture of the bone, which interrupts the integrity of the pelvic ring. Pelvic ring fractures are classified according to the AO (Arbeitsgemeinschaft Osteosynthesefragen) classification, which is the international classification system for bone fractures. – Type A describes a stable pelvic ring fracture.
This means that the fracture is located, for example, in the marginal area of the pelvic blades, but the pelvic ring structure is not affected and is interrupted. This fracture is the most prognostically favourable form, as the pelvic bones do not shift significantly and there are usually no serious concomitant injuries. – Type B fractures sometimes cause instability of the pelvic ring, in which the pelvis can no longer withstand rotational stress.
For this reason, type B fractures are also referred to as rotationally unstable pelvic ring fractures. Such a fracture occurs, for example, when the anterior connection of the pelvic blades, i.e. the symphysis, is torn, allowing the pelvis to be opened up like a book (open-book fracture). – Type C is characterized by complete instability of the pelvic ring. It is therefore unstable not only in the rotational component but also in relation to vertical loading. This is especially the case in complex injuries of the pelvis, in which on the one hand the anterior pelvic ring is affected and on the other hand the sacrum or the joint between the sacrum and the pelvic blades (Articulatio sacroiliaca) is also injured at the same time, thus causing anterior and posterior interruption of the pelvic ring.
Causes
The causes of a pelvic ring fracture are usually severe traumas that affect the body from outside. For example, pelvic ring fractures often occur in falls from great heights or in traffic accidents. In elderly people who have osteoporosis as their underlying disease, pelvic ring fractures occur even in the case of minor trauma, such as simple falls, because osteoporosis reduces bone mass and stability and the bone can be overloaded and break even with light stress.
Symptoms
The main symptom of a pelvic ring fracture is severe pain in the hip region. This pain usually results in a relieving posture of the pelvis and leg. Mobility in the hip is also restricted.
Furthermore, there is often swelling and haematomas above the fracture site. Due to the interruption of the pelvic ring, the pelvis becomes less stable. This results in an abnormal mobility of the pelvic bones, which can be displaced against each other depending on the type of fracture, which is not possible with an intact pelvic ring.
The pelvic ring fracture can even become visible in a pelvic asymmetry which is a path-breaking ocular diagnosis. Particularly with unstable fracture forms, accompanying injuries to adjacent organs and soft tissues can occur. If nerves have been injured, movement in the leg may be restricted or sensitivity disorders of the skin over the hip or leg may result.
If blood vessels are injured, on the one hand there may be circulatory disorders in the adjacent area, and on the other hand bleeding may occur. These bleedings are potentially life-threatening, because on the one hand large blood vessels such as the arteria iliaca, the leg arteries, can be affected and thus enormous blood loss can occur within a short time. On the other hand, an unstable pelvic fracture can cause a large amount of blood to accumulate asymptomatically in the pelvic cavity, i.e. without being noticed.
Due to the instability of the pelvis, the accumulation of blood can push the fracture fragments further apart and thus create space for further blood. There is a high risk of shock and consequent bleeding. The pelvic bones are also adjacent to the bladder, the ureter and the intestine, which can also be injured in fractures, which then becomes visible in the form of bloody urine, for example.
